Optical position detection device

ABSTRACT

An optical position detection device, includes: a light source adapted to emit at least one detection light beam toward one side in a Z-axis direction; a first detector having a light receiving section directed to the one side in the Z-axis direction; a second detector located at a position on the one side in the Z-axis direction, the position being distant from the light source and the first detector, and having a light receiving section directed to the one side in the Z-axis direction; and a position derivation section adapted to derive a position of a object located in a first space between the first detector and the second detector and a position of a object located in a second space on the one side of the second detector in the Z-axis direction based on a light receiving result in the first detector and the second detector.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation application of U.S. application Ser. No.12/968,435 filed Dec. 15, 2010 which claims priority to Japanese PatentApplication No. 2010-052818, filed Mar. 10, 2010 all of which areexpressly incorporated by reference herein in their entireties.

BACKGROUND

1. Technical Field

The present invention relates to an optical position detection devicefor optically detecting the position of a target object.

2. Related Art

As an optical position detection device for optically detecting theposition of a target object, there is proposed a technology of emittinga detection light to the target object located on a first surface of atransmissive plate (light propagation medium) from a second surfacethereof opposite to the first surface, and detecting the detectionlight, which is reflected by the target object and transmitted throughthe transmissive plate to the second surface thereof, with a lightdetector (see JP-T-2003-534554 (Document 1; the term “JP-T” as usedherein means a published Japanese translation of a PCT patentapplication).

Here, the inventors study the optical position detection device foroptically detecting the positions of target objects respectively locatedin two spaces such as the positions of a customer (a target object)located inside a store window and a customer (a target object) locatedoutside the store window, or the positions of a game medium (a targetobject) located inside a cover glass of an amusement device and a player(a target object) located outside the cover glass thereof. However, inthe technology described in Document 1, since the detection result inthe light detector is obtained as a sum of intensities of the detectionlight beams reflected by the respective target objects located in thetwo spaces, there arises a problem that detection of the respectivepositions of the target objects located in the two spaces is notachievable.

SUMMARY

An advantage of some aspects of the invention is to provide an opticalposition detection device capable of detecting the respective positionsof the target objects located in two spaces.

According to an aspect of the invention, there is provided an opticalposition detection device adapted to optically detect a position of atarget object, including a position detecting light source adapted toemit at least one detection light beam toward one side in a Z-axisdirection intersecting an X-axis direction and a Y-axis directionintersecting each other, a first light detector having a light receivingsection directed to the one side in the Z-axis direction, a second lightdetector located at a position on the one side in the Z-axis direction,the position being distant from the position detecting light source andthe first light detector, and having a light receiving section directedto the one side in the Z-axis direction, and a position derivationsection adapted to derive a position of a target object located in afirst space between the first light detector and the second lightdetector and a position of a target object located in a second space onthe one side of the second light detector in the Z-axis direction basedon a light receiving result in the first light detector and a lightreceiving result in the second light detector.

In this aspect of the invention, the position detecting light source isdisposed so as to be directed toward the one side in the Z-axisdirection, and the first light detector and the second light detectorwith the light receiving sections directed toward the one side in theZ-axis direction are disposed at positions distant from each other inthe Z-axis direction. Therefore, when the position detecting lightsource emits the detection light beam toward the one side in the Z-axisdirection, the detection light beam reflected by the target objectlocated in the first space between the first light detector and thesecond light detector is received by the first light detector, and thedetection light beam reflected by the target object located in thesecond space on the one side of the second light detector in the Z-axisdirection is received by the first light detector and the second lightdetector. Therefore, by performing the correction corresponding to thelight receiving result in the second light detector on the lightreceiving result in the first light detector, for example, subtractingthe light receiving result in the second light detector from the lightreceiving result in the first light detector, the intensity of thedetection light beam reflected by the target object located in the firstspace can be obtained, and by using the calculation result of theintensity, the position of the target object located in the first spacecan be derived. Further, the position of the target object located inthe second space can be derived based on the light receiving result inthe second light detector. Therefore, the positions of the targetobjects respectively located in the two spaces (the first space and thesecond space) distant from each other in the emission direction of thedetection light beam can be detected optically.

In this aspect of the invention, it is possible to adopt theconfiguration in which the position derivation section derives theposition of the target object located in the second space based on thelight receiving result in the second light detector, and detects theposition of the target object located in the first space based on adifference between the light receiving result in the first lightdetector and the light receiving result in the second light detector.According to the configuration of this aspect of the invention, it ispossible to perform the correction corresponding to the light receivingresult in the second light detector on the light receiving result in thefirst light detector by a simple process of obtaining the difference.

In this aspect of the invention, it is possible to adopt theconfiguration in which the position derivation section derives aposition in the X-axis direction and a position in the Y-axis directionas the position of the target object.

In this aspect of the invention, it is possible to adopt theconfiguration in which the position derivation section derives aposition in the Z-axis direction as the position of the target object.

In this aspect of the invention, it is preferable to provide atransmissive member located on the one side of the position detectinglight source and the first light detector in the Z-axis direction, andadapted to hold the second light detector. According to theconfiguration of this aspect of the invention, the second light detectorcan be disposed at a position distant from the position detecting lightsource and the first light detector on the one side in the Z-axisdirection. Further, the transmissive member has an advantage that thepresence thereof is inconspicuous.

In this aspect of the invention, it is possible to adopt theconfiguration in which the transmissive member has a plate-like shape,and the first space and the second space are separated by thetransmissive member. According to the configuration of this aspect ofthe invention, it is possible to use the optical position detectiondevice to which the invention is applied to optically detect theposition of a customer (the target object) located inside a store window(the transmissive member) and the position of a customer (the targetobject) located outside. Further, it is possible to use the opticalposition detection device to which the invention is applied to opticallydetect the position of a game medium (the target object) located insidea cover glass (the transmissive member) in amusement equipment coveredby the cover glass and the position of a player (the target object)located outside.

In this aspect of the invention, it is preferable that the second lightdetector is disposed on a side of the first space with respect to thetransmissive member. Since the position detecting light source and thefirst light detector are disposed on the side of the first space withrespect to the transmissive member, by disposing the second lightdetector on the side of the first space with respect to the transmissivemember, all of the position detecting light source, the first lightdetector, and the second light detector can be disposed on the side ofthe first space, and therefore, since there is no need to dispose any ofthe position detecting light source, the first light detector, and thesecond light detector, the configuration in the second space can besimplified.

In this aspect of the invention, it is preferable that the positiondetecting light source emits at least one infrared light beam as thedetection light beam. According to the configuration of this aspect ofthe invention, there can be obtained an advantage that the positiondetection light beam is inconspicuous.

In this aspect of the invention, it is preferable that the positiondetecting light source has a plurality of light emitting elements havingcentral optical axes located differently, and adapted to emit therespective detection light beams to the one side in the Z-axisdirection. According to the configuration of this aspect of theinvention, since the position detecting light source can be constitutedwith the light emitting elements such as LEDs, the configuration of theposition detecting light source can be simplified.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIGS. 1A and 1B are explanatory diagrams schematically showing asubstantial part of an optical position detection device to which theinvention is applied.

FIG. 2 is an explanatory diagram showing a positional relationship ofdetecting light sources and light detectors in the Z-axis direction inthe optical position detection device to which the invention is applied.

FIGS. 3A and 3B are explanatory diagrams showing the positions of theposition detecting light sources and the light detectors in the X-axisdirection and the Y-axis direction in the optical position detectiondevice to which the invention is applied.

FIG. 4 is a block diagram showing an electrical configuration of theoptical position detection device to which the invention is applied.

FIGS. 5A through 5C are explanatory diagrams of position detection lightbeams used in the optical position detection device to which theinvention is applied.

FIGS. 6A and 6B are explanatory diagrams showing the principle of XYcoordinate detection used in the optical position detection device towhich the invention is applied.

FIGS. 7A and 7B are explanatory diagrams showing a method of derivingthe XY coordinate of the target object in the optical position detectiondevice to which the invention is applied.

FIGS. 8A and 8B are explanatory diagrams showing the principle ofdetection of the coordinate of the target object using the differentialin the optical position detection device to which the invention isapplied.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

An embodiment of the invention will be explained in detail withreference to the accompanying drawings. It should be noted that in thefollowing explanation it is assumed that directions intersecting witheach other are X-axis direction, Y-axis direction, and Z-axis direction,respectively. Further, in the drawings referred to below, things areshown assuming one side of the X-axis direction as an X1 side, the otherside thereof as an X2 side, one side of the Y-axis direction as a Y1side, the other side thereof as a Y2 side, one side of the Z-axisdirection as a Z1 side, and the other side thereof as a Z2 side.

Overall Configuration of Optical Position Detection Device

FIGS. 1A and 1B are explanatory diagrams schematically showing asubstantial part of the optical position detection device to which theinvention is applied, wherein FIG. 1A is an explanatory diagram of thelight detector and so on of the position detection device viewed fromthe one side Z1 of the Z-axis direction, and FIG. 1B is an explanatorydiagram of the light detector and so on thereof viewed from the otherside Z2 of the Z-axis direction. FIG. 2 is an explanatory diagramshowing a positional relationship of detecting light sources and lightdetectors in the Z-axis direction of the optical position detectiondevice to which the invention is applied. FIGS. 3A and 3B areexplanatory diagrams showing the positions of the position detectinglight sources and the light detectors in the X-axis direction and theY-axis direction in the optical position detection device to which theinvention is applied, wherein FIG. 3A is an explanatory diagram showingthe positions of a first light detector and so on disposed on the otherside Z2 in the Z-axis direction, and FIG. 3B is an explanatory diagramshowing the positions of a second light detector and so on disposed onthe one side Z1 in the Z-axis direction. It should be noted that inFIGS. 1A, 1B, 3A, and 3B, the light emitting sections of the respectivelight emitting elements and the light receiving sections of therespective light receiving elements are indicated by gray areas.

As shown in FIGS. 1A, 1B, 2, 3A, and 3B, the optical position detectiondevice 10 according to the present embodiment is a device for opticallydetecting the position of the target object, and is provided with theposition detecting light source 12 for emitting the detection lightbeams L2 toward the one side Z1 in the Z-axis direction and the firstlight detector 31 having the light receiving section 310 directed towardthe one side Z1 in the Z-axis direction.

In the present embodiment, the position detecting light source 12 iscomposed of a plurality of light emitting elements 12A, 12B, 12C eachhaving the light emitting section 120 directed toward the one side Z1 inthe Z-axis direction. The central optical axes of the respective lightemitting elements 12A, 12B, and 12C all extend in the Z-axis direction,and the light emitting elements 12A, 12B, and 12C respectively emit thedetection light beams L2 (the detection light beams L2 a, L2 b, and L2c) toward the one side Z1 in the Z-axis direction. Here, the centraloptical axes of the light emitting elements 12A, 12B, and 12C areparallel to each other, but are located differently. More specifically,the central optical axis of the light emitting element 12B is located ata position shifted toward the other side X2 in the X-axis direction andthe other side Y2 in the Y-axis direction from the central optical axisof the light emitting element 12A. Further, the central optical axis ofthe light emitting element 12C is located at a position shifted towardthe one side X1 in the X-axis direction and the other side Y2 in theY-axis direction from the central optical axis of the light emittingelement 12A. It should be noted that the central optical axis of thelight emitting element 12B and the central optical axis of the lightemitting element 12C are shifted from each other in the X-axisdirection, but are located at roughly the same positions in the Y-axisdirection.

Such light emitting elements 12A, 12B, and 12C constituting the positiondetecting light source 12 are all light emitting diodes for emittinginfrared light beams, and emit the detection light beams L2 eachcomposed of an infrared light beam as diverging light beams. Since thedetection light beams L2 each preferably have a wavelength rangeefficiently reflected by the target objects Ob1 and Ob2 such as a fingeror a stylus pen, if the target objects Ob1 and Ob2 are human bodies suchas fingers, infrared light beams (in particular near infrared lightbeams with a wavelength range near to the visible light range and havinga peak wavelength of around 850 nm) having high reflectance on a surfaceof a human body are used as the detection light beams L2.

The first light detector 31 is formed of a device capable of detectingthe infrared light beams such as a photodiode or a phototransistor, andin the present embodiment, a photodiode is used therefor. The firstlight detector 31 and the position detecting light source 12 (the lightemitting elements 12A, 12B, and 12C) are located at positions roughlythe same in the Z-axis direction.

On the lateral side of the first light detector 31, there is disposed afirst reference light emitting element 12S with a light emitting section120 s directed toward the first light detector 31. Such a firstreference light emitting element 12S is also formed of the lightemitting diode for emitting an infrared light beam similarly to theposition detecting light source 12 (the light emitting elements 12A,12B, and 12C), and the light beam emitted from the first reference lightemitting element 12S is used as a reference light beam Lr1.

In the optical position detection device 10 according to the presentembodiment, at the position distant from the position detecting lightsource 12 and the first light detector 31 on the one side Z1 in theZ-axis direction, there is disposed a second light detector 32 with thelight receiving section 320 directed toward the one side Z1 in theZ-axis direction. The first light detector 31 and the second lightdetector 32 are located at positions substantially overlapping with eachother when viewed from the Z-axis direction. Similarly to the firstlight detector 31, the second light detector 32 is formed of a devicecapable of detecting the infrared light beams such as a photodiode or aphototransistor, and in the present embodiment, a photodiode is usedtherefor.

On the lateral side of the second light detector 32, there is disposed asecond reference light emitting element 12T with a light emittingsection 120 t directed toward the second light detector 32. Such asecond reference light emitting element 12T is also formed of the lightemitting diode for emitting an infrared light beam similarly to theposition detecting light source 12 (the light emitting elements 12A,12B, and 12C) and the first reference light emitting element 12S, andthe light beam emitted from the second reference light emitting element12T is used as a reference light beam Lr2.

In the optical position detection device 10 thus configured, asdescribed later, based on the light receiving result in the first lightdetector 31 and the light receiving result in the second light detector32, the position of the target object Ob1 located in a first space 10R1between the first light detector 31 and the second light detector 32 andthe position of the target object Ob2 located in a second space 10R2 onthe one side Z1 of the second light detector 32 in the Z-axis direction.

In the optical position detection device 10 according to the presentembodiment, a transmissive member 16 is located at a position distantfrom the position detecting light source 12 and the first light detector31 on the one side Z1 in the Z-axis direction. The transmissive member16 is formed of a glass plate or a synthetic resin plate capable oftransmitting an infrared light beam, and partitions the space located onthe one side Z1 of the position detecting light source 12 and the firstlight detector 31 in the Z-axis direction into the first space 10R1 andthe second space 10R2. The transmissive member 16 is provided with thesecond light detector 32 and the second reference light emitting element12T mounted thereon, and at the same time, the transmissive member 16 isalso provided with a wiring layer (not shown) for the second lightdetector 32 and the second reference light emitting element 12T. In thepresent embodiment, the second light detector 32 and the secondreference light emitting element 12T are mounted on the side of thefirst space 10R1 out of the both surfaces of the transmissive member 16.It should be noted that the wiring layer is thin, and therefore neverhinders the transmission of infrared light and visible light by thetransmissive member 16. However, since the wiring layer is preferablyinconspicuous, it is preferable that the wiring layer is formed of atransmissive conductive film such as an indium tin oxide (ITO) film oran indium zinc oxide (IZO) film.

Electrical Configuration of Optical Position Detection Device 10

FIG. 4 is a block diagram showing an electrical configuration of theoptical position detection device 10 to which the invention is applied.As shown in FIG. 4, the optical position detection device 10 includes alight source drive section 14 for driving the position detecting lightsource 12 (the light emitting elements 12A, 12B, and 12C), the firstreference light emitting element 12S, and the second reference lightemitting element 12T, and a position derivation section 50 to which thedetection results are output from the first light detector 31 and thesecond light detector 32.

The light source drive section 14 is provided with a light source drivecircuit 140 for driving the light emitting elements such as the lightemitting elements 12A, 12B, and 12C, the first reference light emittingelement 12S, and the second reference light emitting element 12T, and alight source control section 145 for controlling the emission intensityof each of the light emitting elements via the light source drivecircuit 140. The light source drive circuit 140 is provided with a lightsource drive circuit 140 a for driving the light emitting element 12A, alight source drive circuit 140 b for driving the light emitting element12B, and a light source drive circuit 140 c for driving the lightemitting element 12C. Further, the light source drive circuit 140 isalso provided with a light source drive circuit 140 s for driving thefirst reference light emitting element 12S and a light source drivecircuit 140 t for driving the second reference light emitting element12T.

The position derivation section 50 is provided with a signal processingsection 51, an XY coordinate derivation section 52, and a Z coordinatederivation section 53, and derives the position (the XY coordinate andthe Z coordinate) of the target object Ob1 located in the first space10R1 and the position (the XY coordinate and the Z coordinate) of thetarget object Ob2 located in the second space 10R2. The positionderivation section 50 is constituted by, for example, a microprocessorunit (MPU), and thus, it is possible to adopt a configuration ofperforming a process in accordance with performing predeterminedsoftware (an operation program). Further, as the position derivationsection 50, it is also possible to adopt a configuration of performingthe process with a signal processing section 51 using hardware such as alogic circuit. It should be noted that the light source control section145 and the position derivation section 50 are connected to each otherwith a signal line, and the drive of the light emitting elements and thedetection operation in the position derivation section 50 are performedin conjunction with each other.

Configuration of Light Intensity Distribution of Position DetectionLight Beams L2

FIGS. 5A through 5C are explanatory diagrams of the position detectionlight beams used in the optical position detection device 10 to whichthe invention is applied, wherein FIG. 5A is an explanatory diagram ofthe light intensity distribution of the detection light beam L2 aemitted by the light emitting element 12A, FIG. 5B is an explanatorydiagram of the light intensity distribution of the detection light beamL2 b emitted by the light emitting element 12B, and FIG. 5C is anexplanatory diagram of the light intensity distribution of the detectionlight beam L2 c emitted by the light emitting element 12C.

The light emitting elements 12A, 12B, and 12C explained with referenceto FIGS. 1A, 1B, 2, 3A, and 3B have the respective central optical axesdirected to positions different from each other. Further, the detectionlight beams L2 a, L2 b, and L2 c are each a diverging light beam, andsuch a diverging light beam has the highest intensity around the centraloptical axis, and the intensity is lowered continuously as the distancefrom the central optical axis increases. Therefore, the detection lightbeam L2 a emitted from the light emitting element 12A forms the lightintensity distribution L2 a 0 shown in FIG. 5A. In such a lightintensity distribution L2 a 0, the intensity becomes the highest atroughly the center in the X-axis direction on the one side Y1 in theY-axis direction, and the intensity decreases monotonically as thedistance from the highest intensity portion increases. In the lightintensity distribution L2 a 0 according to the present embodiment, theintensity decreases linearly or substantially linearly as the distancefrom the highest intensity portion increases. The detection light beamL2 b emitted from the light emitting element 12B forms the lightintensity distribution L2 b 0 shown in FIG. 5B. In such a lightintensity distribution L2 b 0, the intensity becomes the highest on theother side X2 in the X-axis direction on the other side Y2 in the Y-axisdirection, and the intensity decreases monotonically as the distancefrom the highest intensity portion increases. In the light intensitydistribution L2 b 0 according to the present embodiment, the intensitydecreases linearly or substantially linearly as the distance from thehighest intensity portion increases. The detection light beam L2 cemitted from the light emitting element 12C forms the light intensitydistribution L2 c 0 shown in FIG. 5C. In such a light intensitydistribution L2 c 0, the intensity becomes the highest on the one sideX1 in the X-axis direction on the other side Y2 in the Y-axis direction,and the intensity decreases monotonically as the distance from thehighest intensity portion increases. In the light intensity distributionL2 c 0 according to the present embodiment, the intensity decreaseslinearly or substantially linearly as the distance from the highestintensity portion increases.

Here, the highest intensity portion of the light intensity distributionL2 a 0 and the highest intensity portion of the light intensitydistribution L2 b 0 are shifted from each other in both of the X-axisdirection and the Y-axis direction. Further, the highest intensityportion of the light intensity distribution L2 a 0 and the highestintensity portion of the light intensity distribution L2 c 0 are shiftedfrom each other in both of the X-axis direction and the Y-axisdirection. Further, the highest intensity portion of the light intensitydistribution L2 b 0 and the highest intensity portion of the lightintensity distribution L2 c 0 are shifted from each other in the X-axisdirection. In other words, the highest intensity portion of the lightintensity distribution L2 a 0, the highest intensity portion of thelight intensity distribution L2 b 0, and the highest intensity portionof the light intensity distribution L2 c 0 are located at positionscorresponding to the apexes of an imaginary triangle.

Fundamental Principle of Position Detection

In the optical position detection device 10 according to the presentembodiment, as shown in FIG. 2, the position detection light beams L2(the position detection light beams L2 a through L2 c) emitted from theposition detecting light source 12 (the light emitting elements 12A,12B, and 12C) are reflected by the target objects Ob1 and Ob2, and thensome of the reflected light beams are detected by the first lightdetector 31 and the second light detector 32 to thereby detect thepositions of the target objects Ob1, Ob2. On that occasion, thedetection intensities in the first light detector 31 and the secondlight detector 32 have proportional relationships with the respectivereflection intensities in the target objects Ob1, Ob2, and thereflection intensities in the target objects Ob1, Ob2 are proportionalto the intensities of the detection light beams L2 (the detection lightbeams L2 a, L2 b, and L2 c) at the respective places where the targetobjects Ob1, Ob2 are located. Therefore, the detection intensities inthe first light detector 31 and the second light detector 32 areproportional to the intensities of the detection light beams L2 (thedetection light beams L2 a, L2 b, and L2 c) at the respective placeswhere the target objects Ob1, Ob2 are located, as a result, in the lightintensity distributions shown in FIGS. 5A through 5C.

Further, in the optical position detection device 10 according to thepresent embodiment, the position detecting light source 12 (the lightemitting elements 12A, 12B, and 12C) is disposed so as to be directedtoward the one side Z1 in the Z-axis direction, and the first lightdetector 31 and the second light detector 32 with the light receivingsection directed toward the one side Z1 in the Z-axis direction aredisposed at positions distant from each other on the one side Z1 in theZ-axis direction.

Therefore, in the case in which the target object Ob1 exists in thefirst space 10R1, the detection light beams L2 (the detection lightbeams L2 a, L2 b, and L2 c) emitted from the respective positiondetecting light source 12 (the light emitting elements 12A, 12B, and12C) are reflected by the target object Ob1, then the reflected lightbeams reach the first light detector 31, and the first light detector 31detects the intensities of the reflected light beams.

Further, in the case in which the target object Ob2 exists in the secondspace 10R2, the detection light beams L2 (the detection light beams L2a, L2 b, and L2 c) emitted from the respective position detecting lightsource 12 (the light emitting elements 12A, 12B, and 12C) are reflectedby the target object Ob2, then the reflected light beams reach thesecond light detector 32, and at the same time also reach the firstlight detector 31. Therefore, the intensities of the reflected lightbeams thus reflected by the target object Ob2 are detected by the firstlight detector 31, and at the same time also detected by the secondlight detector 32.

Therefore, in the case in which the target object Ob2 exists in thesecond space 10R2, the intensities of the reflected light beamsreflected by the target object Ob2 can be obtained using the detectionresult in the second light detector 32 irrespective of whether or notthe target object Ob1 exists in the first space 10R1. Therefore, theposition derivation section 50 shown in FIG. 4 can detect the position(the XYZ coordinate) of the target object Ob2 using the method describedlater.

On the other hand, if the target object Ob2 does not exist in the secondspace 10R2 when detecting the position of the target object Ob1 in thefirst space 10R1, the intensities of the reflected light beams reflectedby the target object Ob1 can be obtained from the detection result inthe first light detector 31. It should be noted that in the case inwhich the target object Ob2 exists in the second space 10R2, since thelight beams reflected by the target object Ob2 also enter the firstlight detector 31 in addition to the light beams reflected by the targetobject Ob1, the intensities of the reflected light beams reflected bythe target object Ob1 is unclear even by using the detection result inthe first light detector 31. Therefore, in the present embodiment, theposition derivation section 50 shown in FIG. 4 performs correctioncorresponding to the light receiving result in the second light detector32 on the detection result of the first light detector 31 regardless ofwhether or not the target object Ob2 exists in the second space 10R2 tothereby obtain the intensities of the light beams reflected by thetarget object Ob1 located in the first space 10R1 when detecting theposition of the target object Ob1 in the first space 10R1. Morespecifically, when detecting the position of the target object Ob1 inthe first space 10R1, the position derivation section 50 subtracts theamount corresponding to the light receiving result in the second lightdetector 32 from the detection result of the first light detector 31,and obtains the intensities of the light beams reflected by the targetobject Ob1 located in the first space 10R1 based on the subtractionresult (the difference between the detection result of the first lightdetector 31 and the light receiving result in the second light detector32). Therefore, the position derivation section 50 shown in FIG. 4 candetect the position (the XYZ coordinate) of the target object Ob1 usingthe method described later.

Principle of XY Coordinate Detection

The principle of detection of the XY coordinate of the target object inthe optical position detection device 10 to which the invention isapplied will be explained with reference to FIGS. 6A, 6B, 7A, and 7B.FIGS. 6A and 6B are explanatory diagrams showing the principle of the XYcoordinate detection used in the optical position detection device towhich the invention is applied, wherein FIG. 6A is an explanatorydiagram showing the light intensity distributions of the detection lightbeams, and FIG. 6B is an explanatory diagram showing how the lightintensity distributions of the detection light beams are adjusted sothat the intensities of the detection light beams reflected by thetarget object Ob2 become equal to each other. FIGS. 7A and 7B areexplanatory diagrams showing a method of deriving the XY coordinate ofthe target object in the optical position detection device 10 to whichthe invention is applied.

First Example of Principle of XY Coordinate Detection

In the optical position detection device 10 according to the presentembodiment, as explained hereinabove with reference to FIGS. 1A, 1B, 2,3A, 3B, 4, and 5A through 5C, the position detecting light source 12(the light emitting elements 12A, 12B, and 12C) is provided with thehighest intensity portions at the apexes of the imaginary triangle inthe XY plane, and the light emitting elements have the respective lightintensity distributions different from each other. Therefore, in thepresent embodiment, firstly, the light emitting elements 12A, 12B, and12C are lit sequentially at different timings, and in the meantime, thefirst light detector 31 and the second light detector 32 detect theintensities of the light beams input. Further, the detection results inthe first light detector 31 and the second light detector 32 whenlighting the light emitting element 12A, the detection results in thefirst light detector 31 and the second light detector 32 when lightingthe light emitting element 12B, the detection results in the first lightdetector 31 and the second light detector 32 when lighting the lightemitting element 12C are compared, and the positions of the targetobjects Ob1, Ob2 are detected based on the comparison result.

Hereinafter, an example of detecting the XY coordinate of the targetobject Ob2 in the second space 10R2 will be explained in detail.Firstly, in a first XY coordinate detecting period, when lighting thelight emitting element 12A while putting off the light emitting elements12B, 12C, the light intensity distribution L2 a 0 in which the intensitydecreases monotonically from the XY coordinate position of the lightemitting element 12A to the XY coordinate position of the light emittingelement 12B is formed between the XY coordinate position of the lightemitting element 12A and the XY coordinate position of the lightemitting element 12B as shown in FIG. 6A. Therefore, the detection lightbeam L2 a is reflected by the target object Ob2 in the second space10R2, and some of the reflected light beam is detected by the secondlight detector 32.

Then, in a second XY coordinate detecting period, when lighting thelight emitting element 12B while putting off the light emitting elements12A, 12C, the light intensity distribution L2 b 0 in which the intensitydecreases monotonically from the XY coordinate position of the lightemitting element 12B to the XY coordinate position of the light emittingelement 12A is formed between the XY coordinate position of the lightemitting element 12A and the XY coordinate position of the lightemitting element 12B. Therefore, the detection light beam L2 b isreflected by the target object Ob2 in the second space 10R2, and some ofthe reflected light beam is detected by the second light detector 32.

Then, the ratio between the detection result in the second lightdetector 32 in the first XY coordinate detecting period during which thelight emitting element 12A is lit alone and the detection result in thesecond light detector 32 in the second XY coordinate detecting periodduring which the light emitting element 12B is lit alone is obtained,and if the ratio is equal to d11:d12, it is understood that on the XYplane shown in FIG. 7A the target object Ob2 is located on an imaginaryline L61 (a first straight line) passing through the position, at whichan imaginary straight line L51 connecting the XY coordinate position ofthe light emitting element 12A and the XY coordinate position of thelight emitting element 12B is divided in the ratio of d11:d12, andextending in a direction perpendicular to the straight line L51.

Similarly, in the third XY coordinate detecting period, the lightemitting element 12C is lit while putting off the light emittingelements 12A, 12B. As a result, the detection light beam L2 c isreflected by the target object Ob2 in the second space 10R2, and some ofthe reflected light beam is detected by the second light detector 32.Therefore, the ratio between the detection result in the second lightdetector 32 in the first XY coordinate detecting period during which thelight emitting element 12A is lit alone and the detection result in thesecond light detector 32 in the third XY coordinate detecting periodduring which the light emitting element 12C is lit alone is obtained,and if the ratio is equal to d21:d23, it is understood that on the XYplane shown in FIG. 7B the target object Ob2 is located on an imaginaryline L62 (a second straight line) passing through the position, at whichan imaginary straight line L52 connecting the XY coordinate position ofthe light emitting element 12A and the XY coordinate position of thelight emitting element 12C is divided in the ratio of d21:d23, andextending in a direction perpendicular to the straight line L52.

Therefore, by obtaining the intersection point (the intersection pointof the first straight line and the second straight line) of the twolines L61, L62 in the XY coordinate derivation section 52 shown in FIG.4, the XY coordinate of the target object Ob2 can be detected. Further,by using the value obtained by subtracting the detection result in thesecond light detector 32 from the detection result in the first lightdetector 31 instead of the detection result in the second light detector32, it is possible to detect the XY coordinate of the target object Ob1in the XY coordinate derivation section 52 using the same method as inthe case of the target object Ob2. More specifically, if the ratiobetween the value obtained by subtracting the detection result in thesecond light detector 32 from the detection result in the first lightdetector 31 when lighting the light emitting element 12A alone and thevalue obtained by subtracting the detection result in the second lightdetector 32 from the detection result in the first light detector 31when lighting the light emitting element 12B alone is known, it ispossible to obtain the line L61 (the first straight line; see FIG. 7A)on which the target object Ob1 is located. Further, if the ratio betweenthe value obtained by subtracting the detection result in the secondlight detector 32 from the detection result in the first light detector31 when lighting the light emitting element 12A alone and the valueobtained by subtracting the detection result in the second lightdetector 32 from the detection result in the first light detector 31when lighting the light emitting element 12C alone is known, it ispossible to obtain the line L62 (the second straight line; see FIG. 7B)on which the target object Ob1 is located. Therefore, by obtaining theintersection point of the first straight line and the second straightline, the XY coordinate of the target object Ob1 can be detected.

Second Example of Principle of XY Coordinate Detection

Although in the fundamental principle 1 described above the detectionresult in the first light detector 31 and the detection result in thesecond light detector 32 are used directly for derivation of theposition detection, it is also possible to detect the XY coordinates ofthe target objects Ob1, Ob2 using the differential between the lightemitting element 12A and the light emitting element 12B, and thedifferential between the light emitting element 12A and the lightemitting element 12C.

Hereinafter, an example of detecting the XY coordinate of the targetobject Ob2 in the second space 10R2 will be explained in detail.Firstly, the light emitting element 12A and the light emitting element12B are lit alternately in a standard condition while keeping the lightemitting element 12C in an off state. Then, the line L61 (the firststraight line) explained with reference to FIG. 7A is obtained based onthe current value (a controlled variable) and an adjustment value of thecurrent value (the controlled variable) in the case of controlling thelight emitting elements 12A, 12B so that the detection result in thesecond light detector 32 becomes the same between the first XYcoordinate detecting period in which the light emitting element 12A islit alone and the second XY coordinate detecting period in which thelight emitting element 12B is lit alone. In such a method, the lightemitting element 12A and the light emitting element 12C are litalternately in a standard condition while keeping the light emittingelement 12B in an off state, and the line L62 (the second straight line)explained with reference to FIG. 7B is obtained based on the currentvalue (the controlled variable) and an adjustment value of the currentvalue (the controlled variable) in the case of controlling the lightemitting elements 12A, 12C so that the detection result in the secondlight detector 32 becomes the same between the third XY coordinatedetecting period in which the light emitting element 12A is lit aloneand the fourth XY coordinate detecting period in which the lightemitting element 12C is lit alone, as a result.

More specifically, firstly, when lighting the light emitting elements12A, 12B alternately while keeping the light emitting element 12C in anoff state, the light intensity distribution L2 a 0 shown in FIG. 6A andthe light intensity distribution L2 b 0 shown in FIG. 6A are formedalternately. Here, if the detection result La in the second lightdetector 32 in the first XY coordinate detecting period and thedetection result Lb in the second light detector 32 in the second XYcoordinate detecting period are equal to each other, it becomes that thetarget object Ob2 is located in the middle of the XY coordinate positionof the light emitting element 12A and the XY coordinate position of thelight emitting element 12B. In contrast, in the case in which thedetection result La in the second light detector 32 in the first XYcoordinate detecting period and the detection result Lb in the secondlight detector 32 in the second XY coordinate detecting period aredifferent from each other, the controlled variables (the drive currents)to the light emitting elements 12A, 12B are adjusted so that thedetection results La, Lb become equal to each other as shown in FIG. 6B.Then, by obtaining the ratio between the adjustment value ΔIa of thecontrolled variable to the light emitting element 12A in the first XYcoordinate detecting period and the adjustment value ΔIb of thecontrolled variable to the light emitting element 12B in the second XYcoordinate detecting period, the ratio (d11:d12) explained withreference to FIG. 7A can be obtained.

Further, by performing the method substantially the same as describedabove with the light emitting elements 12A, 12C lit alternately whilekeeping the light emitting element 12B in the off state, the ratio(d21:d23) explained with reference to FIG. 7B can be obtained.

Therefore, as is explained with reference to FIGS. 6A and 6B, the XYcoordinate of the target object Ob2 can be detected. Further, by usingthe value obtained by subtracting the detection result in the secondlight detector 32 from the detection result in the first light detector31 instead of the detection result in the second light detector 32, theXY coordinate of the target object Ob1 can be detected. Further,according to such a method, it is possible to cancel the influence of adisturbance such as the outside light or the temperature.

Fundamental Principle of Z Coordinate Detection

In the optical position detection device 10 according to the presentembodiment, by lighting all of the plurality of light emitting elements(the light emitting elements 12A, 12B, and 12C), the light intensitydistribution for Z coordinate detection obtained by combining the lightintensity distributions explained with reference to FIGS. 5A through 5Cis formed, and in such a light intensity distribution for the Zcoordinate detection, the intensity changes monotonically in the Z-axisdirection, as a result. For example, in the light intensity distributionfor the Z coordinate detection, the intensity decreases linearly orsubstantially linearly toward the one side Z1 in the Z-axis direction.Therefore, the Z coordinate derivation section 53 shown in FIG. 4 candetect the Z coordinates of the target objects Ob1, Ob2 based on thedetection results in the first light detector 31 and the second lightdetector 32 when lighting all of the light emitting elements 12A, 12B,and 21C. More specifically, the Z coordinate of the target object Ob2can be detected based on the detection result in the second lightdetector 32 when lighting all of the light emitting elements 12A, 12B,and 12C. Further, by subtracting the detection result in the secondlight detector 32 from the detection result in the first light detector31 when lighting all of the light emitting elements 12A, 12B, and 12C,the Z coordinate of the target object Ob1 can be detected.

Coordinate Detection Using Reference Light Beams

The optical position detection device 10 according to the presentembodiment is provided with the first reference light emitting element12S having the light emitting section 120 s directed toward the firstlight detector 31, and the second reference light emitting element 12Thaving the light emitting section 120 t directed toward the second lightdetector 32, and the reference light beams Lr1, Lr2 emitted respectivelyfrom the first reference light emitting element 12S and the secondreference light emitting element 12T enter the first light detector 31and the second light detector 32, respectively, with a constantintensity regardless of whether or not the target objects Ob1, Ob2exist. Therefore, by using the comparison result between the detectionlight beams L2 (the detection light beams L2 a through L2 c) emittedfrom the position detecting light source 12 (the light emitting elements12A, 12B, and 12C) and the reference light beams Lr1, Lr2 emitted fromthe first reference light emitting element 12S and the second referencelight emitting element 12T, it is possible to cancel the influence ofthe disturbance such as the outside light or the temperature.

For example, the value obtained by subtracting the detection result inthe first light detector 31 when putting off the light emitting elements12A, 12B, and 12C and lighting the first reference light emittingelement 12S from the detection result in the first light detector 31when lighting the light emitting elements 12A, 12B, and 12C and puttingoff the first reference light emitting element 12S is set as a valuewith disturbance correction in the first light detector 31. Further, thevalue obtained by subtracting the detection result in the second lightdetector 32 when putting off the light emitting elements 12A, 12B, and12C and lighting the second reference light emitting element 12T fromthe detection result in the second light detector 32 when lighting thelight emitting elements 12A, 12B, and 12C and putting off the secondreference light emitting element 12T is set as a value with disturbancecorrection in the second light detector 32. By using such values, it ispossible to cancel the influence of the disturbance such as the outsidelight or the temperature.

Further, it is also possible to detect the coordinates of the targetobjects Ob1, Ob2 using the differential between the position detectinglight source 12 (the light emitting elements 12A, 12B, and 12C) and thefirst reference light emitting element 12S, and the differential betweenthe position detecting light source 12 (the light emitting elements 12A,12B, and 12C) and the second reference light emitting element 12T.

Hereinafter, an example of detecting the Z coordinate of the targetobject Ob2 using the differential between the position detecting lightsource 12 (the light emitting elements 12A, 12B, and 12C) and the firstreference light emitting element 12S, and the differential between theposition detecting light source 12 (the light emitting elements 12A,12B, and 12C) and the second reference light emitting element 12T willbe explained with reference to FIGS. 8A and 8B.

FIGS. 8A and 8B are explanatory diagrams showing the principle ofdetecting the coordinate of the target object Ob2 using the differentialin the optical position detection device 10 to which the invention isapplied, wherein FIG. 8A is an explanatory diagram showing the lightintensity distribution of the detection light beam in the Z-axisdirection, and FIG. 8B is an explanatory diagram showing the lightintensity distribution of the detection light beam in the Z-axisdirection adjusted so that the intensities of the detection light beamsreflected by the target object Ob2 become equal to each other.

In the optical position detection device 10 according to the presentembodiment, when lighting all of the light emitting elements 12A, 12B,and 12C in the standard condition in the detection light beam detectionperiod, the light intensity distribution L2 z 0 in which the intensitydecreases monotonically toward the one side Z1 in the Z-axis directionis formed as shown in FIG. 8A. Therefore, when the target object Ob2 isdisposed in the second space 10R2, the detection light beams L2 arereflected by the target object Ob2, and some of the reflected lightbeams is detected by the second light detector 32. Here, the lightreceiving result L2 z of the detection light beams L2 in the secondlight detector 32 has a certain relationship, for example, aproportional relationship, with the intensity corresponding to theposition of the target object Ob2 in the light intensity distribution L2z 0.

In contrast thereto, when putting off the light emitting elements 12A,12B, and 12C while lighting the second reference light emitting element12T in the reference light detection period, the reference light beamLr2 emitted from the second reference light emitting element 12T ispartially detected by the second light detector 32. Here, the referencelight beam Lr2 is never reflected by the target object Ob2, the lightreceiving result Lr of the reference light beam Lr2 in the second lightdetector 32 is constant irrespective of the position of the targetobject Ob2.

Subsequently, the position derivation section 50 shown in FIG. 4provides the light source control section 145 with an instruction toadjust the controlled variable (the drive current) to the light emittingelements 12A, 12B, and 12C and the controlled variable (the drivecurrent) to the second reference light emitting element 12T so that thedetection result L2 z in the second light detector 32 in the detectionlight beam detection period and the detection result Lr in the secondlight detector 32 in the reference light beam detection period becomeequal to each other. As a result, as shown in FIG. 8B, if both of thedetection result L2 z in the second light detector 32 in the detectionlight beam detection period and the detection result Lr in the secondlight detector 32 in the reference light beam detection period take thesame value Lz, the Z coordinate of the target object Ob2 can be detectedbased on the ratio and the difference between the adjustment value ΔI2 zof the controlled variable with respect to the light emitting elements12A, 12B, and 12C and the adjustment value ΔIr2 of the controlledvariable with respect to the second reference light emitting element12T.

Further, by using the value obtained by subtracting the detection resultin the second light detector 32 from the detection result in the firstlight detector 31 instead of the detection result in the second lightdetector 32, the coordinate of the target object Ob1 in the first space10R1 can be detected. According to such a method, it is possible tocancel the influence of the disturbance such as the outside light or thetemperature.

It should be noted that the differential between the detection lightbeams L2 (the detection light beams L2 a through L2 c) emitted from theposition detecting light source 12 (the light emitting elements 12A,12B, and 12C) and the reference light beams Lr1, Lr2 emitted from thefirst reference light emitting element 12S and the second referencelight emitting element 12T can be applied to the case of performing themethod explained in the first example of the principle of the XYcoordinate detection.

Further, although in the method described above, the intensities of thereference light beams Lr1, Lr2 emitted from the first reference lightemitting element 12S and the second reference light emitting element 12Tare varied, it is also possible that the intensities of the referencelight beams Lr1, Lr2 emitted from the first reference light emittingelement 12S and the second reference light emitting element 12T arefixed.

Major Advantages of Present Embodiment

As explained hereinabove, in the optical position detection device 10according to the present embodiment, the position detecting light source12 is disposed so as to be directed toward the one side Z1 in the Z-axisdirection, and the first light detector 31 and the second light detector32 with the light receiving sections 310, 320 directed toward the oneside Z1 in the Z-axis direction are disposed at positions distant fromeach other in the Z-axis direction. Therefore, when the positiondetecting light source 12 emits the detection light beams toward the oneside Z1 in the Z-axis direction, the detection light beams reflected bythe target object Ob1 located in the first space 10R1 between the firstlight detector 31 and the second light detector 32 are received by thefirst light detector 31, and the detection light beams reflected by thetarget object Ob2 located in the second space 10R2 on the one side Z1 ofthe second light detector 32 in the Z-axis direction are received by thefirst light detector 31 and the second light detector 32.

Therefore, by performing the correction corresponding to the lightreceiving result in the second light detector 32 on the light receivingresult in the first light detector 31, for example, subtracting thelight receiving result in the second light detector 32 from the lightreceiving result in the first light detector 31, the intensities of thedetection light beams reflected by the target object Ob1 located in thefirst space 10R1 can be derived, and by using the derivation result ofthe intensities, the position of the target object Ob1 located in thefirst space 10R1 can be derived. Further, the position of the targetobject Ob2 located in the second space 10R2 can be derived based on thelight receiving result in the second light detector 32. Therefore, thepositions of the target objects Ob1, Ob2 respectively located in the twospaces (the first space 10R1 and the second space 10R2) distant fromeach other in the emission direction of the detection light beams can bedetected optically.

Further, in the present embodiment, the position derivation section 50detects the position of the target object Ob1 located in the first space10R1 based on the difference between the light receiving result in thefirst light detector 31 and the light receiving result in the secondlight detector 32, and according to this configuration, the correctioncorresponding to the light receiving result in the second light detector32 can be performed on the light receiving result in the first lightdetector 31 by the simple process of obtaining the difference.

Further, since the transmissive member 16 for holding the second lightdetector 32 is disposed on the one side Z1 of the position detectinglight source 12 and the first light detector 31 in the Z-axis direction,the second light detector 32 and the second reference light emittingelement 12T can be held at positions distant from each other on the oneside Z1 of the position detecting light source 12 and the first lightdetector 31 in the Z-axis direction. Further, the transmissive member 16has an advantage that the presence thereof is inconspicuous. Further, inthe present embodiment, the transmissive member 16 has a plate-likeshape, and the first space 10R1 and the second space 10R2 are separatedby the transmissive member 16. Therefore, the optical position detectiondevice 10 to which the invention is applied can be used to opticallydetect the position of a customer (the target object Ob1) located inside(the first space 10R1) a store window and the position of a customer(the target object Ob2) located outside (the second space 10R2).Further, the optical position detection device 10 to which the inventionis applied can be used to optically detect the position of a ball or agame medium (the target object Ob1) shaped like a coin moving inside(the first space 10R1) a cover glass (the transmissive member 16) inamusement equipment such as a pinball machine covered by the cover glassand the position of a player (the target object Ob2) located outside(the second space 10R2).

Further, in the present embodiment, the second light detector 32 and thesecond reference light emitting element 12T are disposed on the side ofthe first space 10R1 with respect to the transmissive member 16, and onthe side of the first space 10R1 there are disposed the positiondetecting light source 12, the first light detector 31, and the firstreference light emitting element 12S. Therefore, it is possible todispose all of the position detecting light source 12, the first lightdetector 31, the first reference light emitting element 12S, the secondlight detector 32, and the second reference light emitting element 12Ton the side of the first space 10R1, and therefore, there is no need todispose any of the position detecting light source 12, the first lightdetector 31, the second light detector 32, and so on in the second space10R2. Therefore, the configuration in the second space 10R2 can besimplified.

Further, since the position detecting light source 12 emits the infraredlight beams as the detection light beams, there can be obtained anadvantage that the detection light beams are inconspicuous. Further,since the position detecting light source 12 is provided with theplurality of light emitting elements 12A, 12B, and 12C formed of LEDshaving the central optical axes located differently and for emitting thedetection light beams L2 toward the one side Z1 in the Z-axis direction,the configuration of the position detecting light source 12 can besimplified.

Other Embodiments

Although in the embodiment described above the second light detector 32and the second reference light emitting element 12T are disposed on theside of the first space 10R1 with respect to the transmissive member 16,it is also possible to adopt the configuration in which the second lightdetector 32 and the second reference light emitting element 12T aredisposed on the side of the second space 10R2 with respect to thetransmissive member 16.

Although in the embodiment described above, the position detecting lightsource 12 is provided with the three light emitting elements 12A, 12B,and 12C, it is also possible to adopt the configuration provided withtwo or more than three light emitting elements.

Although in the embodiment described above, the position detecting lightsource 12 is provided with the plurality of light emitting elements 12A,12B, and 12C having the central optical axes located differently and foremitting the detection light beams L2 toward the one side Z1 in theZ-axis direction, it is also possible to use a sheet light sourcecapable of sequentially forming the light intensity distribution used todetect the XY coordinate.

What is claimed is:
 1. An optical position detection device adapted tooptically detect a position of a target object, comprising: a platehaving a plane elongating an X-axis direction and a Y-axis direction; aposition detecting light source adapted to emit light beam toward theplate; a first light detector having a light receiving section directedto a one side in a Z-axis direction intersecting the plate; a secondlight detector located at a position on the one side in the Z-axisdirection, the position being distant from the position detecting lightsource and the first light detector; and a position derivation sectionadapted to derive a position of a target object located in a first spacebetween the first light detector and the second light detector and aposition of a target object located in a second space on the one side ofthe second light detector in the Z-axis direction based on a lightreceiving result in the first light detector and a light receivingresult in the second light detector.
 2. The optical position detectiondevice according to claim 1, wherein the position derivation sectionderives the position of the target object located in the second spacebased on the light receiving result in the second light detector, anddetects the position of the target object located in the first spacebased on a difference between the light receiving result in the firstlight detector and the light receiving result in the second lightdetector.
 3. The optical position detection device according to claim 1,wherein the position derivation section derives a position in the X-axisdirection and a position in the Y-axis direction as the position of thetarget object.
 4. The optical position detection device according toclaim 1, wherein the position derivation section derives a position inthe Z-axis direction as the position of the target object.
 5. Theoptical position detection device according to claim 1, wherein theposition detecting light source emits at least one infrared light beamas the detection light beam.
 6. The optical position detection deviceaccording to claim 1, wherein the position detecting light source has aplurality of light emitting elements having central optical axes locateddifferently, and adapted to emit the respective detection light beams tothe one side in the Z-axis direction.